Re: [PATCH v2 1/1] PCI: pciehp: Skip DLLSC handling if DPC is triggered

[Sinan Kaya]

On 3/17/2021 4:02 PM, Kuppuswamy, Sathyanarayanan wrote:
> My point is, there is no race in OS handlers (pciehp_ist() vs
> pcie_do_recovery())
>  However, Sinan wrote in
>> 2018 that one of the issues with hotplug versus DPC is that pciehp
>> may turn off slot power and thereby foil DPC recovery.  (Power off =
>> cold reset, whereas DPC recovery = warm reset.)  This can occur
>> as well if DPC is handled by firmware. 

It has been a while...

If I remember correctly, there is no race condition if the platform
handles DPC and HP interrupts on the same MSI vector.

If HP and DPC interrupts are handled as MSI-x interrupts, these can
fire out of order and can cause problems for each one.

I hope it helps.